Metallic composition and method of making the same



fitpr. 25a, 1933 s. ROUX, or ORISKANY, NEW YORK, ASSIGNOR re GENERALCABLE coerc- RATION, or NEW YORK, N. Y., A conroaarmn or NEW JERSEYMETALLIC COMPOSITION AND METHOD OF MAKING THE SAME No Drawing.

This invention relates to metallic compositions in the nature of andsimilar to hard and tough materials are required.

This composition has been developed with particular reference to therequirements of av wire-drawing die and although other uses will at oncebe apparent to those skilled in the art, nevertheless, the inventionwill be described with reference to its production and use as awire-drawing die. It will, of course, be understood that the inventionis not limited to the production of die material, and that the use .ofthe material is not limited to the art of wire-drawing.

For a considerable period of time much work and iltperimentation havebeen done in an effort 'to develop materials suitable for dies and toolssuch as would not require tempering or hardening but would naturally besufficiently hard, tough and otherwise suited to the exacting. work tobe performed. In this experimentation carbides of tungsten have provedmost satisfactory and great progress in the art has beenmade along theselines. But no tungsten carbide heretofore made has been found suitablefor tools or dies unless it contained a stronger metal admixedtherewith. It has been i too weak and brittle for tools and too brittleand rough for dies. I

In order to utilize tungsten carbide for tools and dies it has beenfound necessary to form a composition of the same by the inclusion ofone or more additional metals. Usually cobalt or a kindred metal hasbeen used. This has been found to produce a considerably tougher andstronger substance than a simple tungsten carbide alone.

Dies made of a composition of tungsten, carbon and cobalt in the properproportions and by suitable processes have given very encouragingresults. But the metal which is added to tungsten and carbonto form atoughening matrix for the harder particles of tungsten carbide, issofter than Application filed December 3, 1929. Serial No. 411,390.

tungsten carbide and appears to wear away leaving minute pits in theWorking surface of the die resulting in breakage of the die orscratching of the Wire. 7

According to the present invention a composition which is highlysuitable for wire drawing dies is produced solely from tungstenandcarbon without the addition of any further material- This alloy will becalled a blended composition in contradistinction of a compositionproduced by the direct combination of the same materials which latterwill be referred to as a simple or straight composition. Throughout thisspecification and claims the term simple tungsten carbide will be usedto refer to a composition of tungsten and carbon which is formed by theprimary or initial heatproduced combination of tungsten and carbon,whether the composition contains some or all. of the chemicalcombinations of WC,"

W C etc. While no simple or straight composition of tungsten and carbonhas proved at all satisfactory, I have discovered that by preparing aplurality of simple compositions of tungsten and carbon and blendingthem, that a very superior material is produced. This is noteworthy,because not only are the simple compositions which produce the blendedmaterial unsatisfactory alone, but asimple composition having theproportion of partscalculated from the blended material is markedlyinferior if not wholly unsatisfactory.

A composition which has given highly satisfactory results contained thefollowing ingredients:

. Parts Tun sten and carbon having to 1% car on 1 Tungsten and carbonhaving 3% to 4% carbon 1 Tungsten and carbon having 5 to 6% carbon 2Tungsten and carbon having 7% to 8% carbon The aggregate calculatedpercentage of carbon is 5 5/14% to 5 6/7%. The pro portions andpercentages, of course, may be varied within reasonable. limits.

N o theory can as yet be advanced regarding the state of the ingredientsin the final product except that some of the material appears to form amatrix for other portions of the material which have undergone furthercrystallization. It is diilicult, in fact, to determine the state ofingredients in even a simple tungsten carbide composition. Dependin uponinitial proportions, such a simple compositionis usually found tocontain the chemical compounds \VC, W' C, free tungsten and free carbon.X-ray analyses of the blended compositions have been made and have shownthat there is actually a marked difference between the blendedcompositions and the straight compositions. However, sufiicient testshave not yet been made to furnish a. clear statement as to exactly whatthe controlling differences are.

The simple compositions may be prepared in various ways, one of whichmay consist in heating pure powdered tungsten mixed with pure powderedcarbon in a reducing atmosphere for a number of hours at a relativelylow temperature say about 1100 C. (2012 F.). This operation may beeffected by heating in an enclosed vitreous vessel buried in a bed ofcharcoal in a covered resistance furnace.

One illustrative method of combining the simple compositions prepared asabove may be as follows: The several simple compositions in powderedform are mixed in proper proportions and placed in a carbon mold closedby carbon plugs. A carbon plunger enters one end of the mold and ismovable by a metal plunger so as to be capable of compressing thecontents of the mold at the desired time.

Continuing the illustration, the filled mold is placed betweenwater-cooled electrodes with sufficient pressure on the electrodes toestablish good electrical contact with the mold; but no pressure isplaced upon the plunger as yet. The current is turned on to sinter themixture in the mold. After a temperature of about 2500 F. is attainedthe current is turned off and simultaneously therewith sudden pressureis brought upon the plunger and through it upon the sintered mixture inthe mold. This appears to produe a coalescence of the sintered material.It is then left to cool between the watercooled electrodes to form ablank. If desired the pressure may be and usually will be maintainedduring cooling.

Assuming that the resulting material is to be used for dies the blankthus formed is now drilled to form the die. It is observed in drillingthat the material has a granular appearance but may be drilled withoutunusual difliculty. Apparently it is not so hard to drill as a blankmade with cobalt as a matrix material for the tungsten carbide. Itpolishes to a fine smooth surface which in use wears down evenly andwithout pitting. This is believed to be due to the fact that thematerial is homogeneous, that is to say, uniformly hard, since there isno matrix of softer material to wear back to produce pits between thelarger particles of tungsten carbide. The pits referred to are notnecessarily large, and ordinarily cannot be observed without the use ofa microscope. In wire drawing work pits so small as to be. observableonly at about 100 diameters of magnification may harmfully affect theoperation of the die. The present material does not contain pits (whichmay be designated as voids either before or after they are partlyexposed at the surface) which are large enough to cause ill effects inwire drawing work. so it may be referred to as being substantially freefrom voids.

The die thus formed proves to be sufficiently tough for wire drawingpurposes. Experience has shown that the wear on the dies is very slow,for example, of dies in actual servlce a number have now run over 17million feet of copper wire drawing from .072 to .064 in one pass andkeeping the wire within 1% of gauge, without re-drilling and since thewear is not very appreciable it appears that the maximum life will bemuch greater.

Not only is the service unusually high but consistent good results havebeen realized,

whereas dies of other compositions have given more or less uncertainresults even when made as nearly under duplicated conditions aspossible. It will be realized that great adantages accrue in this art inbeing able to consistently duplicate good results.

While one embodiment of the invention has been described in detail forpurposes of illustration, it is to be understood that various changesand modifications may be made within the scope of the appended claims.

What I claim is:

1. The method of making a metallic composition which comprises, making aplurality of simple tungsten carbide compositions at approximately 1100C. or 2012 F., one having a carbon content of to 1%, a second having acarbon content of 3%% to 4%, a third having a carbon content of ti to 6%and a fourth having a carbon content of 7 to 8%, mixing these severalsimple compositions and sintering in a closed carbon mold, cutting offthe sintering heat at approximately 2500 F. and simultaneously applyingpressure upon the sintered material in the mold and cooling the mold andcontents.

diverse simple separately formed portions gether a number of simpleseparately formed carbides of tungsten varying in carbon content buttaken in such proportions that the calculated carbon content of themixture is between 5% and 6% without any other metal or binding agentand sintering the whole together under pressure.

5. The method of making a hard metallic.

composition which comprises mixing together a plurality of powderedsimple separately-formed carbides of tungsten ofvarying carbon contentfrom to 8% but taken in such proportions that the carbon content of themixture is between 5% and 6%, heating the mixture to sinteringtemperature and exerting sudden pressure at approximately the same timethat the heating is stopped. a

6. As an article of manufacture, acomposition body formed from aplurality of or bodies of tungsten and carbon without the addition ofany other materials and having properties similar to a compositionformed, as for example, by sintering together the following pre-formedtungsten carbide portions:

Parts 5% to 1% carbon content 3 to 4% carbon content 1 5 to 6% carboncontent 2 7 to 8% carbon content 3 and which is smooth and without poreswhich are of a size to take up metal and become clogged during thedrawing of metals such as copper, which is uniformly hard throughout anygiven section or surface whereby it willnot become pitted in use as adrawing die, and which is coherent and tough enough to be used as adrawing die, the material being markedly stronger in ten sile strengththan any material formed from tungsten and carbon alone at a single,operation.

7. The method of forming composition bodies of tungsten and carbon alonewithout any other metals or binding materials which are compact,non-porous, strong and smooth so as to be suitable for working toolssuch as drawing dies, which comprises, separately forming a plurality ofportions or bodies of tungsten and carbon each different from the other,reducing each portion to finely powdered condition, mixing the severalportions together without the inclusion of any other material, andsintering the mixture and applying pressure to the metal while hot.

Intestimony whereof, I have signed my name to this specification this25th day of November, 1929.

ADRIAN P. ROUX.

